COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Auxiliary Power Units
AD/APU/10 GTCP 85 Series APU Axial Containment 8/95
Applicability: AlliedSignal Aerospace GTCP85 Series Auxiliary Power Units (APU's) incorporating a one piece cast turbine rotor, except those APU's installed on Boeing 737 and British Aerospace BAC 1-11 series aircraft.
Requirement: Install an exhaust centrebody in accordance with AlliedSignal Aerospace Alert Service Bulletin GTCP85-49-A6831 or AlliedSignal Aerospace Service Bulletin GTCP85-49-6919 as applicable.
Note: FAA AD 95-07-03 also refers.
Compliance: (a) Flight operable APU's are to be modified no later than 30 June 1997.
(b) APU's that are ground operable only are to be modified no later than 30 June 1998.
Background: There have been at least two uncontained failures where turbine wheel fragments have exited the APU exhaust axially and damaged the aircraft.
B737 and BAC 1-11 aircraft are exempt from this requirement because the APU exhaust configuration on these aircraft is such that aircraft damage is highly improbable in the event of an uncontained turbine wheel failure which liberates fragments axially.